The present invention relates to a shirred sausage casing and to a process for its manufacture. The shirred sausage casing is also referred to as "shirred stick".
A shirred sausage casing is disclosed in European Patent Application No. 0,037,543, which suggests the use of the device disclosed in U.S. Pat. No. 4,185,358 for shirring sausage casings possessing areas of increased thickness in the form of glued seams. By means of this particular shirring device, the tubular casing is automatically twisted during the shirring operation. According to this publication, twisting is, for example, effected in such a way that a shirring mandrel is used which is smaller than the conventionally employed shirring mandrel. As a result, the glued seam zone of a tubular casing is arranged, in a helically wound manner, about the longitudinal axis of the shirred tubular casing. However, the process results in the casing having far less than 10 helical windings of the seam zone per 10 m of casing length, which is insufficient for a high shirring ratio. Moreover, it is impossible in this way to achieve a reproducible pitch of the helically wound seam zone. Also, the hollow space in the interior of the shirred stick does not have a perfectly circular cross section, due to the fact that at least part of the relatively thick seam zone is displaced into the hollow space during shirring.
It has also been proposed, for example in European Patent Application No. 0,054,162, to helically twist a sausage casing with a glued seam during shirring by using a shirring device in accordance with any of U.S. Pat. Nos. 2,819,488, 3,619,854, 3,594,857 or 3,766,603. The number of windings per 10 m of tube length varies between 0.5 and 10. More than 10 windings per 10 m of tube length cannot be achieved by helically twisting the tube during shirring. Moreover, European Patent Application No. 0,054,162 does not indicate how the windings of the glued seam extend across the main-folds of the shirred stick. It is also not suggested to increase the breaking strength of the shirred casing by a special arrangement of the glued seam, particularly since, according to this prior publication, importance is only attached to the number of windings of the glued seam.